1. Field of the Invention
The invention lies in the field of conveyor technology and relates to a device and to a method for the transfer of flexible, flat objects, in particular printed products, between two conveyors.
2. Description of Related Art
In conveyor technology and in particular in the field of printing technology, it is often necessary to transfer objects from grippers of a first gripper conveyor into grippers of a second gripper conveyor. Printed products coming from a printing machine are held and conveyed by a gripper.
Various ways as to how such a transfer between two gripper conveyors may occur is sketched in EP-B 1321410. EP-A 1834911 describes a further transfer device, with which individual objects are transferred from first grippers to second grippers. The second grippers are arranged in each case below the first grippers. The first grippers are opened in a transfer region, so that the objects, on account of gravity, slide into the co-moved open second grippers, which are thereupon closed.
Often, the mutual distance of the grippers between the first and the second gripper conveyor is different, and as a rule the distance of the first grippers is smaller than the distance of the second grippers. In the state of the art, the speeds of the two gripper conveyors are therefore selected adapted to one another such that the first and the second grippers are synchronised in the transfer region and execute no movements relative to one another seen in the conveyor direction, in order not to upset the transfer process by way of displacement in the conveyor direction.
On separating out objects transferred in pairs, but also with the transfer of individual objects from a first gripper to a second one, special demands are made to the extent that the object edge which is not gripped is reliably positioned such that it is led as precisely as possible into the open gripper jaw of the second gripper. This, above all, is important with flexible products such as e.g. printed products, since on conveying, they are only held at one product edge and may change their position or deform on account of external influences such as e.g. drafts.
With EP-A 1834911, the distance of the first to the second gripper conveyor path is constant in the transfer region. The objects which are released by the first gripper are led into the second gripper supported by gravity by way of a support device in the form of two laterally engaging spirals which define a support surface co-moved with the second gripper taking over. They are temporarily not held during the transfer. Also with EP-B 1321410, the first gripper is opened before the synchronously co-moved second gripper is closed.
It is the object of the invention to further improve known devices and methods for the transfer of flexible, flat objects from a first gripper conveyor to a second gripper conveyor, in particular in order to be able to transfer and/or collate the objects in a reliable and easily controllable manner.